Collaborative Research: Advancing Measurements of Supermassive Black Holes with Triaxial Stellar-Dynamical Models

超大质量黑洞(SMBH)是星系的基本组成部分。发现SMBH既需要精致的观测数据集，也需要广泛的数值模拟。30多年的研究工作已经在附近的星系中产生了大约100个SMBH质量。然而，当地SMBH的普查在几十亿个太阳质量以上仍然非常不完整。此外，只有少数研究对利用恒星运动和气体运动或在不同建模假设下获得的SMBH质量进行了直接比较。当执行这一重要检查时，通常会发现两个或两个以上的因素存在分歧。研究小组将在恒星运动建模方面取得重大进展。他们将使用这一工具来发现宇宙中新的大质量SMBH，并直接比较使用恒星和气体确定的SMBH质量测量结果。该计划将改善对当地SMBH的普查，以及我们对SMBH和星系如何随着时间的推移而增长的理解。该项目通过为不同背景的高中生和大学生提供研究机会和职业指导，进一步造福社会。暑假期间，学生们将沉浸在研究中。他们将与主要研究人员及其团队在涉及SMBH及其附近星系的详细研究的项目上密切合作。研究团队将填充和扩大SMBH和宿主星系之间关联的稀疏上端，并识别和调查由于恒星动力学建模假设(轴对称和三轴形状)和不同的动力学示踪物(恒星和分子气体)导致的SMBH质量可能的差异。他们将利用我们新修订的三轴轨道建模程序、大型望远镜上的高灵敏度积分场光谱仪和基于ALMA的气体动力学SMBH质量测量所提供的令人兴奋的最近机会。他们将应用我们的三轴代码，并开发一种现代参数搜索策略，以实现对高维参数空间的高效无网格采样，并快速收敛到最佳匹配模型。然后，他们将把这项技术应用于用Keck和Gemini望远镜上的积分场光谱仪观察到的两个星系样本：具有大的弥散恒星核心的巨型椭圆星系和具有现有分子气体动力学SMBH质量的早期类型星系。该计划将把三轴轨道建模从一种罕见的技术提高到一种标准技术，将已知的100亿太阳质量范围内的超大质量SMBH的数量增加一倍，对两种主要的动态SMBH质量测量方法进行关键评估，并使之能够研究星系的内在形状和恒星轨道分布。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Supermassive black holes (SMBHs) are fundamental components of galaxies. Discovering a SMBH requires both exquisite observational datasets and extensive numerical modeling. Over 30 years of research effort have produced about 100 SMBH masses in nearby galaxies. The local SMBH census, however, is still highly incomplete above a few billion solar masses. Moreover, only a handful of studies have made direct comparisons of SMBH masses obtained using the motions of stars and using the motion of gas or under different modeling assumptions. When this important check was performed, it was common to find disagreements of a factor of two or more. The research team will make major advances modeling stellar motions. They will apply this tool to uncover a new population of massive SMBHs in the Universe and to make direct comparisons of SMBH mass measurements determined using stars and gas. The program will improve the census of local SMBHs and our understanding of how SMBHs and galaxies grow over time. The project further benefits society by giving research opportunities and career mentoring to high school and college students from diverse backgrounds. The students will be immersed in research during the summer. They will work closely with the principal investigators and their teams on projects involving the detailed study of SMBHs and nearby galaxies.The research team will populate and expand the sparse upper-end of the correlations between SMBH and host galaxies, as well as identify and investigate possible discrepancies in SMBH masses resulting from stellar-dynamical modeling assumptions (axisymmetric and triaxial shapes) and from different dynamical tracers (stars and molecular gas). They will exploit the exciting recent opportunities afforded by our newly revised triaxial orbit modeling code, highly sensitive integral-field spectrographs on large telescopes, and ALMA-based gas-dynamical SMBH mass measurements. They will apply our triaxial code and develop a modern parameter search strategy to enable efficient grid-free sampling of high-dimensional parameter space and rapid convergence to best-fit models. They will then apply this technique to two galaxy samples observed with integral field spectrographs on the Keck and Gemini telescopes: giant elliptical galaxies with large, diffuse stellar cores and early-type galaxies with existing molecular gas-dynamical SMBH masses. The program will advance triaxial orbit modeling from a rarity to a standard technique, double the number of known ultra-massive SMBHs in the mass range of ten billion suns, provide critical assessment of the two main dynamical SMBH mass measurement methods, and enable the study of galaxy intrinsic shapes and stellar orbital distributions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.